[csswg-drafts] Pull Request: [scroll-animations-1] Use CSSTypedOM instead of strings (#5213)

majido has just submitted a new pull request for https://github.com/w3c/csswg-drafts:

== [scroll-animations-1] Use CSSTypedOM instead of strings (#5213) ==
Use appropriate CSSTypedOM instead of DOMStrings in the API. Fixes #5213.

Changes:
 - For offsets use `CSSNumberish or ScrollTimelineAutoKeyword` instead of DOMString
 - When computing effective scroll offset check the offset actual type and interpret it accordingly
 - To improve ergonomics we accept double (via CSSNumberish) and interpret unit less values as being in pixels.
 - Update examples to showcase the API and add noted to clarify the usage.



See https://github.com/w3c/csswg-drafts/pull/5300